Portable bending brakes are constructed of an array of support castings that are held together by an appropriate frame. The castings are provided with a clamp and a bending structure that clamps and bends sheet material at the open ends of the castings. Such portable bending brakes are designed to be lightweight for use at job sites for bending relatively thin gauge sheet material, such as metal or plastic sheets, used to sheath portions of homes or other buildings. For example, portable bending brakes are used to bend aluminum and vinyl sheets into custom-formed siding and trim pieces to cover existing wood trim during new construction or remodeling.
Portable bending brakes, however, do have limitations that present problems for an operator attempting to make certain trim shapes. In particular, portable bending brakes are limited in how small, how close together, and how close to the edge of a workpiece that bends can be made. Consequently, various commonly needed trim shapes cannot be made easily on portable bending brakes, and must therefore be formed by difficult and time-consuming processes on the brake and may not always fit properly when installed on the house or building.
For example, one type of wood trim found on most houses is termed "brick mold" which consists of a double bend in the sheet material that is used to surround window and door frames. Portable bending brakes are not generally capable of making the small bends necessary to form brick mold, and consequently the operator is forced to make a loose fitting trim shape in a difficult and time-consuming manner that lacks the brick mold detail.
Another problem facing operators of portable bending brakes during installation of siding is how to keep long, flat sections of trim commonly used on fascia (the face of a roof overhang), from waving and rippling, or "oil canning" as it is termed in the art. One solution is to create a small rib along the center of the trim section to provide stiffening. Again, a portable bending brake is not capable of making such a small bend, and usually the rib must be fabricated in a factory.